• More than 200 Syrians, mostly civilians, were massacred in Tremseh, near Hama, when it was bombarded by helicopter gunships and tanks and then stormed by militiamen who carried out execution-style killings, opposition activists said.

• The UN's monitoring mission in Syria confirmed the use of heavy weapons in Tremseh including tanks and helicopters, before the alleged massacre took place. General Robert Mood, the head of the mission, said military operations were continuing and his monitors had been prevented from entering Tremseh.

• International envoy Kofi Annan said the Syrian government's use of heavy weapons in Tremseh was a violation of its apparent commitment to his peace plan. He said he was "shocked and appalled" by reports from Tremseh. Annan is due to hold talks with Russia on Monday.

• The opposition Syrian National Council has repeated its call for the UN security council to pass a binding resolution against the Assad government in the wake of the killings. Britain's foreign secretary William Hague said diplomats in New York will continue to press for a Chapter VII resolution in the face of repeated objections from Russia.

• Firas Tlass, the businessman brother of defected general Manaf Tlass, still sees a role for Bashar al-Assad in Syria. In an interview with Asharq al-Awsat he said the most suitable solution for Syria would be for Assad to hand power to a joint council ... "which is what we might call a mixture of the Egyptian and Yemeni solutions".

People from a neighbouring opposition village travelled to Tremseh to warn villages of a possible attack by shabiha militia from al-Safsafeyeh, a nearby Alawite village, he via Skype. They urged women and children to flee Tremseh, he said.

Today more than 70 people were buried, he claimed "The rest of the martyrs are still left in the fields, they couldn't reach them until now," he said.

Hamadee said:

A big number of the young men were killed in the field when they were trying to escape the army attack. Helicopters targeted them by heavy machine guns while they were driving their motorcycles - while they were fleeing the village.

Today the people of Tremseh opened a house that was burned by troops. They found two people who were burned alive. My sister told me that the only two doctors in the village were targeted by mortar shells. Both doctors were killed in their houses.

Hamadee claimed gunmen executed wounded people found in house. They then shot the man who was looking after the wounded in front of his family, he claimed. "After that they burnt his corpse in front of his wife," he said.

Hamadee claimed 150 armoured vehicles were used in the attack.

Shelling started at dawn and continued until the afternoon, but shelling "with clever mortars" of specific houses continued afterwards.

He said: "Between 3pm and 8pm troops and shabiha searched the houses of civilians, made arbitrary arrests, made field executions of some people inside the village."

The troops arrested Hamadee's brother-in-law, who is a lawyer. "They said 'you have a computer in your house, you must be an activist'.

Hamadee's sister said the shelling of the area was "very heavy".

Hamadee said:

She said many houses were levelled to the ground. She said one shell killed a father in a neighbouring house."

She said one soldier tried to assure her, he said 'we are not shabiha, we are soldiers from the Syrian army. But later came a new group which contained many members of the shabiha [including the group who arrested her husband].

He claimed Tremseh did not have a strong presence of rebel troops, but it did include troops who had defected.

Rural areas around Hama are largely liberated, he said, but the government forces control the checkpoints.

These checkpoints are very fortified. The regime can at any time bring reinforcements to these checkpoints and can move its vehicles in order to attack any village.

The Free Syrian Amry can't defend the villages because it only has light weapons. "That's why we see such horrible massacres," he said.

Asked about his sister, Hamadee said:

In the beginning she was very scared. We saw fear in her eyes. And we saw horror and fear in the eyes of her child. Right now she is OK.

5.00pm: The Syrian government news agency has a little more detail about the car bomb in Damascus earlier today (see 1.59pm). It says the vehicle, a Mercedes, was parked at the roadside and the bomb was detonated remotely.

2.38pm: A leading member of the Syrian opposition claims the timing of the Tremseh massacre was aimed at boosting morale of Assad's armed supporters and scuppering attempts to find a political solution.

Khalid Saleh, executive member of the Syrian National Council, insisted the reported atrocities were well documented.

Asked why alleged massacres often coincide with UN security council meetings, he said:

From the Assad regime's perspective it is very clear that any political or international solution at this point will mean the end of the Assad regime. I think the Assad regime, in committing all these massacres, is really talking to [its] shabiha, to his forces on the ground. I think these massacres unfortunately increase the morale of the Assad gangs. It is the same thing when they shot down the Turkish airplane.

Assad doesn't really care about the international community. What he is focused on is winning the battle on the ground, so he is doing all he can to raise the morale of his troops. Unfortunately it is a sad reality that committing massacres like these will increase the morale of the gangs ...

The Syrian regime has made it very clear that they are killing any chance for a peaceful transition.

The Tremseh massacre is well documented and not being exaggerated by activists, Saleh insisted. He pointed out that the initial deathtoll came down from 250 to 200 because of a desire to record the casualties accurately.

We would love for the international media to come and see the horrible massacres that are taking place. At this point in time the Syrian revolution is the most well document revolution - about 1.5 million videos - that have tracked every victim, his name, his family, where he lived. So it is difficult to say these are exaggerated.

Saleh was part of a SNC delegation that met Russia's foreign minister Sergei Lavrov, and his team in Moscow this Wednesday.

He said Russia's support for Assad was inconsistent and showing signs of wavering.

The Russians are still talking about a dialogue with the Assad regime, this is not something that the forces on the ground, or Syrian National Council, are willing to accept.

Although the Russians say they are not holding firmly to Assad, in one sentence, in the next sentence, they are asking us still to have a dialogue with him. They are giving us two different positions within 60 seconds.

Asked if the SNC left Moscow empty handed, he said:

We made some progress ... it was semi-promising that the Russians are saying they are not holding firm to Assad and they are not insisting on him remaining in power.

Some parts of the Russian delegation were more understanding than other parts. They understand that there is a very heavy price for their delay. They understand that their delaying tactics are really supporting the Assad [regime] and the killing of civilians.

The Tremseh massacre will put more pressure on Russia and China at the security council, but it is unlikely to shift their positions, Saleh said.

If the security council "fails to meet its legal and moral obligations" there will be more bloodshed in Syria, he said. But the revolution will go on with or without outside help, he claimed. He added: "At this point we don't believe that the Annan mission has any chance of succeeding."

1.59pm: There are reports that a car bomb has exploded in the Mezze district of Damascus, near the Iranian embassy.

Today's banner is a little more difficult to make out than usual. As ever there is more from the Banners from Kafranbel Facebook group, including a cartoon placard of Putin and Assad as Leonardo DiCaprio and Kate Winslet in Titanic.

1.18pm: Compared to the turmoil elsewhere in Syria, Damascus is still relatively calm. But how long will that last? An article in the Washington Post, by an unnamed special correspondent, says the city now seems ready to explode.

Anti-regime graffiti are scribbled on the walls in almost every neighbourhood. At night, the sound of shelling in nearby suburbs that have fallen under rebel control echoes through the streets, disturbing the sleep of rich and poor alike. Flying — or tayara — protests, in which small groups stage sudden and swift demonstrations, are increasing even in some of the more upmarket neighbourhoods of the city.

One reason for the changing mood, the article says, is the large number of Syrians from other parts of the country who have flocked to the capital seeking refuge from the conflict.

They have brought with them stories of pain and injustice, infecting Damascenes with some of the anger that has sustained the uprising elsewhere for about 16 months.

"The presence of the refugees made us live the tragedy, not only hear about it or read about it as if in a book," said Samer, 30, a Damascus-based activist who took in a family of 10 from the Bayadeh area of Homs in March.

1.02pm:Bahrain: Private Eye magazine has used freedom of information law to obtain a series of emails (heavily redacted) relating to Bahrain's attendance at Britain's biggest arms fair last year.

It seems that after initially banning Bahrain from the fair, the British government relented under pressure from the Defence & Security Organisation (the government arms sales department) and allowed it to attend.

The government also arranged dinner dates and "stand visits" with arms firms, and the two Bahraini National Guard reps attended a BAE Systems reception on 13 September. There were also meetings with defence ministers Gerald Howarth and Lord Astor, a "lunch hosted by Air Vice Marshal Nigel Maddox" in the "VIP Dining Area" and a 45-minute presentation on unmanned drones.

• The UN's monitoring mission in Syria confirmed the use of heavy weapons in Tremseh including tanks and helicopters, before the alleged massacre took place. General Robert Mood, the head of the mission, said his monitors stand ready to enter Tremseh if there is a truce.

• International envoy Kofi Annan said the Syrian government's use of heavy weapons in Tremseh was a violation of its apparent commitment to his peace plan. He said he was "shocked and appalled" by reports from Tremseh. Annan is due to hold talks with Russia on Monday.

• The opposition Syrian National Council has repeated its call for the UN security council to pass a binding resolution against the Assad government in the wake of the killings. Britain's foreign secretary William Hague said diplomats in New York will continue to press for a Chapter VII resolution in the face of repeated objections from Russia.

• Firas Tlass, the businessman brother of defected general Manaf Tlass, still sees a role for Bashar al-Assad in Syria. In an interview with Asharq al-Awsat he said the most suitable solution for Syria would be for Assad to hand power to a joint council ... "which is what we might call a mixture of the Egyptian and Yemeni solutions".

He suggested it strengthened the case for a binding Chapter VII resolution at the security council, something the Russians have consistently blocked.

In a statement Hague said:

More than 200 men, women and children appear to have been killed in this latest atrocity. Everything we have seen of the Syrian regime's behaviour over the last seventeen months suggests that these reports are credible. They demand a united response from the international community.

We have two urgent priorities – to establish an accurate account of what happened in Tremseh so that those responsible can and will be held to account; and to agree urgent action at the United Nations Security Council.

To that end, the UN mission in Syria must be able to access Tremseh quickly and without hindrance so they can carry out an independent investigation into what has happened and who is responsible.

And we will redouble our efforts to agree a Chapter VII resolution of the UN security council. This would compel the Syrian regime to fulfil the commitments it has made under the Annan plan, to withdraw its military from residential areas, and establish a transitional government as called for by Kofi Annan and endorsed by the P5 and Arab League. It should be a legally binding security council resolution with teeth, that creates a trigger for sanctions if the Assad regime does not comply. British diplomats in New York will continue negotiations on a resolution at the security council today.

11.53am: The head of the UN's monitoring mission Robert Mood has confirmed the use of heavy weapons, including helicopters, in Tremseh.

At his press briefing this morning in Damascus he also confirmed that monitors could only enter the area when there is a truce.

He said:

From our presence in the Hama province we can verify continuous fighting yesterday in the area of Tremseh. This involved mechanized units, indirect fire as well as helicopters.

Unsmis stands ready to go in and seek verification of the facts, if and when there is a credible ceasefire ...

If we have credible cessation of violence and a local ceasefire, we stand ready to go in with a larger team to verify the facts on the ground. What we have verified today is that there was on going fighting yesterday involving mechanized units, involving indirect fire impact and involving helicopters. This is what we have seen from a distance of 5 to 6kms.

Will it be more possible to verify more facts in the coming hours and days? I don't know. I sincerely hope so. Because everyone not in the least the Syrian people are really served better by having these facts established.

Elsewhere, Mood claimed that Unsmis had made some progress in reducing violence.

He said:

Unsmis has been engaging in some localities to facilitate local dialogues between the parties as they seek to find a step by step way to build confidence and stop the negative spiral of violence.

In this context, encouraging progress has been made by the parties in Deir Ezzor. We observe a significant reduction of violence and growing confidence in a possible step by step approach to stop the violence.

Mood also called on the security council to end its gridlock over Syria, and extend the mandate of monitoring mission.

For the sake of the Syrian people we now need genuine and effective leadership from the security council. The security council should unite on a plan that meets the aspirations of the Syrian people – and is accepted by the parties. Government and opposition must be willing to make concessions and sit down at the negotiating table. If this happens, the presence of the mission is credible and the mission can contribute to improving the situation on the ground and facilitate further dialogue.

11.26am: International envoy Kofi Annan says the confirmed use of tanks and helicopters in Tremseh is a breach of the Assad regime's commitment to his peace plan.

In an unusually critical statement of the Syrian government he says:

I am shocked and appalled by news coming out of the village of Tremseh, near Hama, of intense fighting, significant casualties, and the confirmed use of heavy weaponry such as artillery, tanks and helicopters.

This is in violation of the government's undertaking to cease the use of heavy weapons in population centres and its commitment to the six-point plan.

Unsmis stands ready to go in and seek verification of the facts, if and when circumstances permit. The freedom of movement of the observers must be respected.

I condemn these atrocities in the strongest possible terms. It is yet another reminder of the nightmare and the horrors Syrian civilians are being subjected to.

It is desperately urgent that this violence and brutality stops and more important than ever that governments with influence exert it more effectively to ensure that the violence ends – immediately.

Photograph: Frank Baron for the Guardian

11.19am: Shadow foreign secretary Douglas Alexander (pictured) says the reported massacre in Tremseh underlines "the urgency with which the conflict in Syria must be brought to an end".

In a statement he added:

It is vital that the UN security council reconvene and press for further sanctions and a full scale arms embargo in light of this continuing and appalling violence.

With the mandate for the UN observers due to expire next week, the international community must be united and resolute in pursuing the steps necessary to stop the killing and allow the political transition to begin.

11.11am: Getting through to opposition sources in and around Tremseh is proving difficult even by Syrian standards.

The Guardian has to tried to make contact with 10 sources in the area this morning with no success.

Reuters says communications to area have been cut, which may explain the relative paucity of video footage from Tremseh.

Some activists said their accounts were based on satellite phone calls to residents in Tremseh, but that they had lost contact early in the morning.

Security forces were reported to have cut Internet and phone connections before they shelled and stormed the town on Thursday. Opposition groups said this was making it difficult for them to obtain and upload videos of the scene.

11.09am: The head of the monitoring mission in Syria, Maj Gen Robert Mood, said UN observers are ready to go to the Tremseh massacre site "if there is a ceasefire", al-Arabiyya TV reports.

The UN mission is due to end in a week unless its mandate is renewed.

10.48am: Firas Tlass, the businessman brother of defected general Manaf Tlass, still sees a role for Bashar al-Assad in Syria. The Saudi-owned newspaper, Asharq al-Awsat (in Arabic), interviewed him by phone in Paris:

Regarding what awaits the Syrian president, Bashar al-Assad, Tlass sees that Bashar al-Assad is still part of the solution (even though he is a large part of the crisis), saying that the most suitable solution for Syria would be for Bashar al-Assad to hand power to a joint council ... "which is what we might call a mixture of the Egyptian and Yemeni solutions".

For more on the Tlass family, see yesterday's article by Julian Borger, Martin Chulov and Kim Willsher

Russia called on Annan to work more closely with the Syrian opposition, it says citing a foreign ministry source

A ministry source told RIA news agency that Annan would discuss the crisis with Foreign Minister Sergei Lavrov in Moscow on Monday, although neither Russia nor the envoy have announced the visit.

"To be honest, we do not see our partners being as ready (as Russia) to work with the opposition, and Kofi Annan is the main mediator of this process," deputy foreign minister Gennady Gatilov was quoted as saying by Interfax.

"Unfortunately, so far we don't see any practical results from his and his team's contact with the opposition," he said.

He said reports that shabiha entered the village and began executing civilian cannot be confirmed, but he added: "The fact that so many sources have published so many narratives which are basically consistent suggests that there is validity to these details."

A detailed account by activists before news of the massacre emerged said at 6.00am on Thursday, a convoy of 25 vehicles carrying army and security forces, three armoured vehicles and five trucks mounted with artillery passed West through the town of Muharda and headed toward the village of Tremseh.

"They blockaded the village from all four sides and began violently and randomly firing on houses as a helicopter flew overhead. As the attack happened the electricity and telephone lines were cut. Residents gathered in the streets in a state of fear and panic. They were unable to flee because of the blockade from every side," the report posted on activist Web sites said.

"After that, fierce clashes erupted between the heroic Free Syrian Army and Assad's army. Assad's gangs attacked the village school and completely destroyed it. Many people were injured."

9.28am: Activists first raised alarm about a potential massacre in Tremseh in the early hours of yesterday morning.

Below the line Brown Moses points out that activist Maryam Saleh tweeted this yesterday morning:

Shabiha from the regime loyalist al-Safsafeyeh village were seen headed towards al-Traimse. A massacre is feared. #pt#Hama#Syria

The group the Syrian Revolution General Commission has this unverified account of the chronology:

From the early hours of this morning, the village was besieged with tanks at 5am with all entrances and exits to the village were closed off and it was shelled for over two hours. The electricity to the area was cut and all lines were down. The regime security forces then stormed the Altreimseh with support of helicopters above in preparation for the entry of the regime shabih [pro-government militia] from the pro-regime suburbs that surround Tremseh.

To stop this bloody madness which threatens the entity of Syria, as well as peace and the security in the region and in the world, requires an urgent and sharp resolution of the Security Council under Chapter VII (of the U.N. Charter) which protects the Syrian people.

We expect members of the Security Council to assume total responsibility to protect defenceless Syrians against these shameful crimes," said the SNC, which added that the latest killings ranked "among the more infamous genocides of the Syrian regime.

Forces of the fascist regime in Syria committed today [Thursday] a new massacre that killed, thus far, over 220 martyrs in the town of Tremseh, west of Hama. A heinous criminal act was added to the regime's track record of horrors which do not discriminate between man, woman, or child. The same methodology, tools and means as previous massacres was used: forces of the regime's army shelled the town, Shabiha then stormed the town and killed and slaughtered individuals and then and burned the wounded and the bodies of the martyrs. In the past few months, the regime has orchestrated and implemented gruesome massacres to send messages, with the blood of the Syrian people, to the international community in reaction to every move (by the international community) to escalate pressure against the regime.

The massacre is said to have taken place in the village of Tremseh, starting early Thursday morning, when government forces are alleged to have surrounded the village and opened fire with mortars and artillery. Then an Alawite pro-government militia, the Shabiha, are reported to have moved into Tremseh and started carrying out executions.

This video (WARNING: GRAPHIC) contains images of the wounded and dead Syrian rebels say were killed in Tremseh.

A statement by the Hama Revolutionary Council, which reported that more than 220 people were killed, said:

The town of Tremseh, which is located on al-Sqeilabiya Road and is about 35km away from Hama, was subjected to violent shelling by the Assad army since the early hours of the morning. A convoy composed of 25 cars filled with army personnel and security forces ...and a number of shabiha thugs from surrounding villages headed toward the town. They surrounded the village from all sides and prevented residents from leaving. The shelling lasted for about 5 continuous hours. Tens were killed as a result of the violent arbitrary shelling. Afterwards, shabiha thugs from surrounding pro-regime villages (al-Safsafah – Tal Sikeen – Aseela – Hanjoor) stormed the village and committed another horrific massacre. Those who survived the shelling were slaughtered.

Fadi Sameh, an opposition activist from Tremseh, told Reuters.

It appears that Alawite militiamen from surrounding villages descended on Tremseh after its rebel defenders pulled out, and started killing the people. Whole houses have been destroyed and burned from the shelling.

Sameh said he had left the town before the reported massacre but was in touch with residents.

It was impossible to confirm the reports immediately, in part due to the state ban on foreign and independent journalists, but if confirmed, the killings would represent the single biggest massacre in 16 months of the Syrian revolt.